Bitbucket is a hosting site for the distributed version control systems (DVCS) Git and Mercurial. The service offering includes an issue tracker and wiki, as well as integration with a number of popular services such as Basecamp, Flowdock, and Twitter.
BitBucket is a great resource other then Github. The key differences between the two is that clearly Github has the larger community and Bitbucket's monetization model is different. They are owned by a parent company that has a diversified portfolio of tools and services. Because of this, they offer support for free private repos.
Github on the other hand, Github IS the business and they will monetize in the only way they can, by you using their tools.
Back in your terminal window, copy the contents of your public key file.
For example, in Linux you can cat the contents.
In Mac OSX the following command copies the output to the clipboard:
pbcopy < ~/.ssh/id_rsa.pub
Paste the copied public key into the SSH Key field:
Press Add key. The system adds the key to your account. Bitbucket sends you an email to confirm addition of the key.
For more information about how to set up with BitBucket, they have a full documentation resource.